JP2012006673A - Sheet carrying device, document reading device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet carrying device and a document reading device, in which a skew-corrected sheet can be carried stably by reducing the effect of a turn portion depending the thickness of the sheet to be carried.SOLUTION: The sheet carrying device includes: a turn guide portion 40 provided in a carrying path for carrying a document, the turn guide portion guiding the document so that the document is substantially inverted; a pull-out roller 12 provided on the upstream side in the document carrying direction of the turn guide portion 40; and an intermediate roller 14 provided on the downstream side thereof. The device further includes a sensor S1 which is disposed in the carrying path to detect the thickness of the document, and a control means 100 which varies, according to the paper kind of the document detected by the sensor S1, the rotating speed of at least one roller of the pull-out roller 12 and the intermediate roller 14. The control means 100 variably controls the rotating of the roller so that the sheet carrying speeds by the pull-out roller 12 and the intermediate roller 14 are substantially identical to each other.

Description

  The present invention includes a turn guide portion that guides a sheet so as to be substantially reversed in a conveyance path in which the sheet is conveyed, and a first conveyance roller and a second conveyance downstream thereof are provided upstream of the turn guide portion in the sheet conveyance direction. The present invention relates to a sheet conveying apparatus provided with a roller, the sheet conveying apparatus, a document reading apparatus, and an image forming apparatus.

  The above-described type of sheet conveying apparatus is well known, and is used, for example, in a scanner, and also in an original reading apparatus mounted on an image forming apparatus such as a copying machine or a facsimile. In this type of document reading device, there is a sheet-through type that is read by a position-fixed reading unit while transporting a document, and this sheet-through type document feeder is a mechanism for reading an image while transporting a document. One of the features is that productivity can be increased as compared with the type (belt type) in which the original is stopped and the scanner of the main body is moved to read the original. And nowadays, where work efficiency is required, the demand for improving productivity, that is, increasing the document reading speed, is increasing.

  In such a sheet-through type document feeder, it is necessary to read an image without deviation, and for this purpose, it is required to convey the document without tilting. However, when the roller arrangement is asymmetric with respect to the center in the width direction of the document to be conveyed, for example, when a document of a specific size is set with reference to the end face or when documents of a plurality of sizes are mixedly loaded, On the other hand, the conveyance force is biased, and document bending (hereinafter referred to as skew) occurs, which is a problem for reading an image without bending.

  In response to these problems, a pair of pull-out rollers downstream of the separation unit and upstream of the turn guide unit is used as an abutment roller, and the leading end of the document abuts against this to correct the skew. Methods for adjusting the amount are already known.

  In such an apparatus, the skew-corrected document is transported from the pull-out roller to the intermediate roller, the document is transported to the turn guide portion by the transport force of the pull-out roller and the intermediate roller, and is reversely transported before reading processing. However, in such a skew correction method, when the corrected document passes through the intermediate roller and comes into contact with the turn guide portion, a force that causes the document to return to the original state according to its rigidity against bending at the turn portion. Since it exhibits, the conveyance load increases. This increase in the conveyance load is more noticeable with a highly rigid original such as cardboard. Therefore, the intermediate roller has insufficient conveyance force against the increased load, the slip rate increases, and the pull-out roller has a large conveyance force. Thus, the document is pushed into the intermediate roller.

At this time, if the conveying force of the pull-out roller is not uniform in the width direction, the document is conveyed in a state where a skew occurs such that the side where the document is strongly pressed by the pull-out roller is preceded.
From the above, when a highly rigid document such as thick paper is conveyed, the phenomenon of being conveyed in a skewed state appears remarkably.

  Therefore, in Patent Document 1, for the purpose of performing highly reliable skew correction, not only skew correction by abutment on the upstream pull-out roller but also the linear speed of the pull-out roller with respect to the linear speed of the downstream intermediate roller. Control method that corrects the skew by abutting and bending to the nip part of the intermediate roller pair, decelerating the linear velocity of the pull-out roller after abutment, and adjusting the amount of deflection according to the type of document Is disclosed.

  However, the skew correction means of Patent Document 1 does not consider the influence of the turn guide portion, and if the arrangement of the rollers is asymmetric with respect to the center in the width direction of the document, a large skew occurs, and the state Thus, since the leading edge of the document is pushed into the intermediate roller and penetrates, the problem that the skew correction by the abutting cannot be sufficiently performed cannot be solved.

  In view of the above-described conventional problems, the present invention reduces the influence of the turn portion due to the thickness of a sheet to be conveyed, and can stably convey a skew-corrected sheet and a document reading apparatus. The purpose is to provide.

  In order to solve the above-described problems, the present invention includes a turn guide portion that guides a sheet to be substantially reversed in a conveyance path in which the sheet is conveyed, and a first conveyance roller is provided upstream of the turn guide portion in the sheet conveyance direction. And a second conveying roller downstream thereof, a detection unit that is disposed in the conveyance path and detects the sheet type of the sheet, and according to the sheet type of the sheet detected by the detection unit Control means for varying the rotational speed of at least one of the first transport roller and the second transport roller, and the control means has a sheet transport speed by the first transport roller and the second transport roller. A sheet conveying apparatus is proposed in which the rotational speed of the roller is variably controlled so as to be substantially the same.

  According to the present invention, the detection unit includes a thickness detection unit that detects a sheet thickness, and the control unit detects the first conveyance roller and the second conveyance roller according to the sheet thickness detected by the thickness detection unit. It is advantageous to control the rotational speed of at least one of the rollers.

  Further, according to the present invention, the detecting means includes a thickness detecting means for detecting the sheet thickness and a width detecting means for detecting the width of the sheet, and the sheet thickness and width detecting means detected by the thickness detecting means detect the sheet thickness. It is advantageous that the control means controls the rotational speed of at least one of the first transport roller and the second transport roller according to the sheet width.

  Furthermore, the present invention includes a thickness detecting means for detecting the sheet thickness by the detecting means, and a length detecting means for detecting the length in the sheet conveying direction, and the sheet thickness detected by the thickness detecting means. It is advantageous that the control means controls the rotational speed of at least one of the first conveying roller and the second conveying roller according to the sheet length detected by the length detecting means.

  Further, in order to solve the above-described problem, the present invention includes a turn guide portion that guides a sheet to be substantially reversed in a conveyance path in which the sheet is conveyed, and a first guide is provided upstream of the turn guide portion in the sheet conveyance direction. In a sheet conveying apparatus provided with a conveying roller and a second conveying roller downstream thereof, according to a paper type designating unit for designating the paper type of the sheet, and the paper type of the sheet designated by the paper type designating unit And a control unit that varies a rotational speed of at least one of the first transport roller and the second transport roller, and the control unit is configured so that a sheet transport speed by the first transport roller and the second transport roller is substantially equal. A sheet conveying apparatus is proposed in which the rotation speed of the roller is variably controlled so as to be the same.

  In the present invention, the paper type designating unit designates information on the rigidity of the sheet, and the control unit designates the first conveying roller and the second conveying according to the designated rigidity of the sheet. It is advantageous to control the rotational speed of at least one of the rollers.

  Further, according to the present invention, the paper type designating unit designates sheet thickness information, and the control unit judges the strength of rigidity from the sheet thickness information, and the first conveying roller and the second conveying unit. It is advantageous to control the rotational speed of at least one of the rollers.

Furthermore, according to the present invention, it is advantageous that the control means variably controls the rotation speeds of both the first transport roller and the second transport roller.
Furthermore, in the present invention, it is advantageous that the control means makes the rotational speed of the first transport roller constant and variably controls the rotational speed of the second transport roller.

Still further, according to the present invention, it is advantageous that the control means makes the rotational speed of the second transport roller constant and variably controls the rotational speed of the first transport roller.
Furthermore, in order to solve the above-described problems, the present invention proposes an original reading apparatus that conveys an original using the sheet conveying apparatus according to any one of claims 1 to 10.

  Furthermore, in order to solve the above-mentioned problems, the present invention proposes an image forming apparatus characterized in that an image read by the document reading apparatus according to claim 11 is recorded and formed.

  According to the present invention, it is possible to significantly reduce the occurrence of skew by controlling the rotation speeds of the first conveyance roller and the second conveyance roller in accordance with differences in conveyance conditions such as paper type and conveyance load. Further, a stable and good quality document reading can be obtained with the document reading apparatus using the sheet conveying apparatus, and a stable and high quality recorded matter can be obtained with the image forming apparatus using the document reading apparatus.

1 is an overall view showing an outline of a document reading apparatus provided with a sheet conveying apparatus according to the present invention. FIG. 6 is a block diagram illustrating a configuration of feeding control of the document reading apparatus. 3 is a block diagram illustrating a configuration of reading control of the document reading apparatus. FIG. FIG. 3 is a plan development view illustrating a configuration of a sheet conveying apparatus. FIG. 6 is a side view illustrating a partial configuration of the sheet conveying apparatus. 6 is a flowchart illustrating a control example of the sheet conveying apparatus according to the present invention. It is a flowchart which shows the modification of the control of FIG. It is a flowchart which shows another modification of control of FIG. It is a flowchart which shows the example of control of other embodiment of the sheet conveying apparatus which concerns on this invention. It is a flowchart which shows the modification of the control of FIG. It is a flowchart which shows another modification of control of FIG. 10 is a flowchart illustrating a control example of still another embodiment of the sheet conveying apparatus according to the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram showing an embodiment of a sheet conveying apparatus according to the present invention. The sheet conveying apparatus according to the present embodiment conveys an original to be read to a fixed reading apparatus unit and conveys an image while conveying it at a predetermined speed. The apparatus is used in an automatic document feeder (hereinafter referred to as ADF) that performs reading. The basic configuration, operation, and operation of the ADF will be described based on the schematic diagram of the apparatus in FIG. 1 and the control block diagrams in FIGS.

  In FIG. 1, an original setting unit A for setting a read original bundle, a separation feeding unit B for separating and feeding originals one by one from the set original bundle, and primary abutting alignment of the fed originals. Resist part C that works to pull out and convey the original after alignment, turn part D that turns the conveyed original and conveys the original surface toward the reading side (downward), and contacts the surface image of the original A first reading / conveying unit E for reading from below the glass; a second reading / conveying unit F for reading the back side image of the document after reading; a paper discharge unit G for discharging the document whose front and back sides have been read out; The stacking unit H is configured to stack and hold originals after completion, the driving units 101 to 105 and 113 to 115 that drive these conveying operations, and the controller unit 100 that controls a series of operations.

  The original bundle 1 to be read is set on the original table 2 including the movable original table 3 with the original surface facing upward. Further, the width direction of the document bundle 1 is positioned in a direction perpendicular to the conveyance direction by a side guide (not shown). The document set is detected by the set filler 4 and the set sensor 5 and transmitted to the main body control unit 111 by the I / F 107. Further, an outline of the length in the document transport direction is determined by the document length detection sensors 30 to 32 provided on the document table surface. As the document length detection sensors 30 to 32, a reflection type sensor or an actuator type sensor that can detect even one document is used, and it is possible to determine at least whether the document size is vertical or horizontal. The sensor is arranged in

  The movable document table 3 can be moved up and down in the directions a and b shown in the drawing by a bottom plate raising motor 105. When the set filler 4 and the set sensor 5 detect that a document is set, the bottom plate raising motor 105 is moved. Is moved forward so that the movable document table 3 is raised so that the uppermost surface of the document bundle contacts the pickup roller 7.

  The pickup roller 7 is moved by the pickup motor 101 in the c and d directions shown in the figure by a cam mechanism, and the movable table 3 is lifted and pushed by the upper surface of the original on the movable table 3 to rise in the c direction and the table lift detection sensor 8. The upper limit can be detected. When the print key is pressed from the main body operation unit 108 and a document feed signal is transmitted from the main body control unit 111 to the controller unit 100 via the I / F 107, the pickup roller 7 rolls by the forward rotation of the paper feed motor 102. Rotation is driven to pick up several (ideally one) originals on the original table 2. The rotation direction of the pickup roller 7 is the clockwise direction in the drawing in which the uppermost document is conveyed to the sheet feeding port.

  The paper feed belt 9 is driven in the paper feed direction by the normal rotation of the paper feed motor 102, and the reverse roller 10 is driven to rotate in the reverse direction to the paper feed by the normal rotation of the paper feed motor 102. The document is separated, and only the uppermost document can be fed. More specifically, the reverse roller 10 is in contact with the paper feeding belt 9 at a predetermined pressure, and when the paper is in direct contact with the paper feeding belt 9 or through a single document, the reverse roller 10 rotates. Therefore, when two or more originals enter between the paper feeding belt 9 and the reverse roller 10, the revolving force is set to be lower than the torque of the torque limiter. The roller 10 rotates in the clockwise direction, which is the original driving direction, and pushes back an excess original, thereby preventing double feeding.

  The original separated by the action of the paper feeding belt 9 and the reverse roller 10 is further fed by the paper feeding belt 9, and the leading edge is detected by the abutting sensor 11 and further abuts against the pull-out roller 12 stopped. . Thereafter, the sheet is fed by a predetermined distance from the detection of the abutting sensor 11, and as a result, the paper feeding motor 102 is stopped while being pressed against the pull-out roller 12 with a predetermined amount of bending, thereby supplying the paper. The driving of the paper belt 9 is stopped. At this time, the pickup motor 101 is rotated so that the pickup roller 7 is retracted from the upper surface of the original and the original is fed only by the conveying force of the paper feed belt 9, whereby the leading edge of the original enters the nip between the upper and lower roller pairs of the pull-out roller 12. Then, tip alignment (skew correction) is performed.

  The pull-out roller 12 has the skew correction function and is a roller for conveying the skew-corrected document after separation to the intermediate roller 14 and is driven by the reverse rotation of the paper feed motor 102. At this time (when the paper feed motor 102 reverses), the pull-out roller 12 and the intermediate roller 14 are driven, but the pickup roller 7 and the paper feed belt 9 are not driven.

  A plurality of document width sensors 13 are arranged in the depth direction and detect the size in the width direction perpendicular to the conveyance direction of the document conveyed by the pull-out roller 12. Further, the length of the document in the conveyance direction is detected from the motor pulse by reading the leading and trailing edges of the document with the abutment sensor 11.

  When the document is transported from the resist section C to the turn section D by driving the pull-out roller 12 and the intermediate roller 14, the transport speed at the resist section C is set to be higher than the transport speed at the reading transport section E. The processing time for sending the document to the reading unit is shortened.

  When the leading edge of the document is detected by the reading inlet sensor 15, before the leading edge of the document enters the nip between the upper and lower roller pairs of the reading inlet roller 16, deceleration is started at the same time as the document reading speed is made equal to the reading conveyance speed. Then, the reading motor 103 is driven forward to drive the reading inlet roller 16, the reading outlet roller 23, and the CIS outlet roller 27. When the registration sensor 17 detects the leading edge of the document, it decelerates over a predetermined conveyance distance, temporarily stops before the reading position 20, and transmits a registration stop signal to the main body control unit 111 via the I / F 107. . Subsequently, when a reading start signal is received from the main body control unit 111, the document whose registration has been stopped is transported at an increased speed so as to rise to a predetermined transport speed until the leading end of the document reaches the scanning position. At the timing when the leading edge of the document detected by the pulse count of the reading motor 103 reaches the reading unit, a gate signal indicating an effective image area in the sub-scanning direction on the first surface is sent to the main body control unit 111 and the first reading unit is set to the document. Sent until the trailing edge is removed.

  In the case of single-sided document reading, the document that has passed through the reading conveyance unit E is conveyed to the paper discharge unit G through the second reading unit. At this time, when the leading edge of the original is detected by the paper discharge sensor 24, the paper discharge motor 104 is driven to rotate forward to rotate the paper discharge roller 28 counterclockwise. In addition, the discharge motor pulse count from the detection of the leading edge of the document by the discharge sensor 24 reduces the discharge motor drive speed immediately before the trailing edge of the document comes out of the nip of the pair of upper and lower rollers of the discharge roller 28 to discharge the document. Control is performed so that the document discharged onto the tray 29 does not jump out.

  In the case of double-sided document reading, the second image reading unit 25 is detected at the timing when the document leading end reaches the second image reading unit 25 by the pulse count of the reading motor 103 after the discharge sensor 24 detects the document leading end. Then, a gate signal indicating an effective image area in the sub-scanning direction is transmitted from the controller unit 100 until the trailing edge of the document passes through the reading unit. The second reading roller 26 serves as a reference white part for obtaining shading data in the second reading unit as well as suppressing floating of the original in the second reading unit.

  In the ADF configured and operated in this way, the turn part D is provided with a turn guide part 40, and the rollers on the upstream side in the transport direction of the turn guide part 40 are the pull-out roller 12 and the intermediate roller 14, and the turn guide part 40 A roller on the downstream side in the transport direction is constituted by a reading entrance roller 16.

Next, the mechanism of the skew generation that the present invention intends to solve will be described.
In FIG. 4, since the reverse roller 10 becomes a load when the document is conveyed, the rotational speed and conveying force of the pull-out roller 12 are set larger than those of the intermediate roller 14. In the ADF in which the document is set with reference to the end surface, the roller portion 12a of the pull-out roller 12 is asymmetrically arranged with respect to the center in the document width direction. It is easy to generate. Even if the skew is not the end face reference but the center reference ADF, the situation can be the same when the user does not set the original properly or when the originals having different width sizes are mixedly loaded.

  Further, as shown in FIG. 5, when the leading end of the document passes through the intermediate roller 14 and comes into contact with the turn guide unit 40, the document bent by the turn guide unit 40 tries to return to the original flat state according to its rigidity. In order to demonstrate the force to do, conveyance load increases. This increase in the conveyance load is more noticeable with a highly rigid document such as cardboard. As described above, the rotation speed and the conveyance force of the pull-out roller 12 are larger than those of the intermediate roller 14. Therefore, the slip rate of the intermediate roller 14 increases due to insufficient conveyance force with respect to the increased load. Although the conveyance speed is reduced, the pull-out roller 12 having a large conveyance force hardly slips and pushes the document into the intermediate roller.

  In the ADF of the present embodiment, the roller portion of the pull-out roller 12 is disposed at the back, so that the pull-out roller 12 pushes the document into the intermediate roller 14 on the back side, and the decrease in the conveyance speed due to the effect of slip is small. However, on the near side, since the force with which the document is pushed by the pull-out roller 12 is weaker than that on the far side, the decrease in the document conveyance speed due to the influence of slip becomes large. Therefore, the document is conveyed downstream of the intermediate roller 14 with a large skew at the back.

From the above, when a highly rigid document such as thick paper is conveyed, the phenomenon of being conveyed in a skewed state appears remarkably.
In the present invention, the following measures are taken in order to suppress the occurrence of such skew.

  First, in the configuration of the ADF in FIG. 1, a thickness detection sensor S <b> 1 is added between the separation feeding unit B and the pull-out roller 12 as means for detecting the thickness of the document. Considering the time until the motor reaches a desired rotation speed, etc., since it is desired to detect the thickness information of the document at the earliest possible stage, in this embodiment, the thickness detection sensor S1 is disposed immediately after the document is separated. Yes. As long as the thickness detection sensor S1 can adjust the rotational speed of the intermediate roller 14 or the pull-out roller 12 after detecting the thickness of the original, the other end may be used. It is desirable that the roller is arranged upstream of the roller for adjusting the rotation speed. As the thickness detection means for detecting the thickness of the document, a detection means using a known ultrasonic sensor or minute displacement sensor can be employed.

  FIG. 6 is a flowchart showing the control operation of the present invention. Note that the sheet conveyance speed by the pull-out roller 12 and the intermediate roller 14 is related to the rotational speed of each of the pull-out roller 12 and the intermediate roller 14 and the diameter of each roller, but the control flow of this example is the embodiment shown in FIGS. Accordingly, both of the roller diameters are the same, and this is an example in which a difference occurs in the sheet conveyance speed due to a difference in rotational speed.

  In FIG. 6, when the document set sensor 5 detects document setting (step P1) and receives a document feed signal from the main body control unit 111 (step P2), the rotational speed Vt of the intermediate roller 14 is set to the initial value Vt0, The rotation speed Vp of the pull-out roller 12 is set to the initial value Vp0 (step P3). Note that Vt0 ≦ Vp0 is set in consideration of the reduction in the document conveying speed of the pull-out roller due to the separation load. The feeding of the document is started, the document is separated and conveyed (step P4), and when the leading edge of the document reaches the thickness detection sensor S1, the thickness of the conveyed document (paper thickness t) is detected (step t). P5), the information is sent to the CPU.

  Next, it is determined whether or not the paper thickness t of the conveyed document is thicker than a predetermined paper thickness t1 (step P6). If the paper thickness t of the original is thicker than the predetermined paper thickness t1, the document is Judged to be cardboard. Based on this information, the rotational speed Vt of the intermediate roller 14 is set to Vt1, and the rotational speed Vp of the pull-out roller 12 is set to Vp1 (step P7).

  When the paper thickness t of the conveyed original is smaller than t1, it is determined whether or not the original paper thickness t is larger than the predetermined paper thickness t2 (step P8), and is larger than the predetermined paper thickness t2. If it is thick, it is determined as plain paper, and based on the information, the rotational speed Vt of the intermediate roller 14 is set to Vt2, and the rotational speed Vp of the pull-out roller 12 is set to Vp2 (step P9). If the paper thickness t of the original conveyed in step P8 is smaller than the predetermined paper thickness t2, it is determined that the original is thin (step P10), and the rotational speed Vt of the intermediate roller 14 is based on the information. Is set to Vt3, and the rotation speed Vp of the pull-out roller 12 is set to Vp3. However, the predetermined value of the paper thickness is t1> t2, the predetermined value of the rotation speed of the intermediate roller 14 is Vt1> Vt2> Vt3, and the predetermined value of the rotation speed of the pull-out roller 12 is Vp1 <Vp2 <Vp3. . Further, the relationship between the rotational speed Vt1 of the intermediate roller 14 for thick paper and the rotational speed Vp1 of the pull-out roller 12 is Vt1 ≧ Vp1, and for thin paper, it is Vt3 ≦ Vp3. The reason why the rotational speed is set as described above is that the document transport speeds of the intermediate roller 14 and the pull-out roller 12 are preferably equal in order to prevent skew, but the intermediate roller 14 slips and transports the document. This is because the speed decreases. In the case of thin paper, slippage at the intermediate roller 14 hardly occurs, and the load on the separating unit is affected, leading to a reduction in the document conveying speed of the pull-out roller 12.

  Then, the original is conveyed through the turn guide section 40 at the set rotation speed of the roller, and when the leading edge of the original reaches the nip-in sensor 15 in front of the reading section (step P11), the intermediate roller 14 and the pull-out roller 12 The rotation speed is changed to Vs which is the same as the document reading speed (step P12), and the document reading operation is performed (step P13). Here, an example is shown in which the abutting skew correction is not performed by the reading entrance roller 16 before the reading operation on the assumption that the document is conveyed at a higher speed. However, skew prevention and abutting skew correction by the above-described control are shown. By combining these, more reliable (no skew) conveyance becomes possible. As described above, by controlling the rotation speed of the pull-out roller 12 and the rotation speed of the intermediate roller 14 according to the type of document and the conveyance status so that the document conveyance speed of both rollers is equal, the occurrence of skew is greatly increased. Can be reduced.

Incidentally, the occurrence of skew is caused by an asymmetric arrangement with respect to the center in the width direction of the roller portion 12a of the pull-out roller 12. The influence of this asymmetry varies depending on the width of the document.
Therefore, the present invention can be controlled as in the flowchart shown in FIG.

In FIG. 7, steps P1 to P6 and P11 to P13 in this figure are the same as steps P1 to P6 and P11 to P13 in FIG.
If the paper thickness t of the original is larger than the predetermined paper thickness t1 in step 6, the width size sensor 13 detects the original width w (step P7A), and whether the original width w is smaller than the predetermined width w1. Determination is made (step P8A). The predetermined width w1 is appropriately set according to the asymmetric arrangement with respect to the center in the width direction of the roller portion 12a of the pull-out roller 12. In this control, the rotation speed of the pull-out roller 12 is fixed and the intermediate roller 14 is set to be variable. Therefore, if the document width w is smaller than the predetermined width w1, the rotation of the intermediate roller 14 is assumed to be affected by the asymmetric arrangement. The speed Vt is set to Vt1 (step P9A). If the document width w is larger than the predetermined width w1, the influence of the asymmetric arrangement is alleviated, so the rotational speed Vt of the intermediate roller 14 is set to Vt2 (step P9B). If the paper thickness t of the original is smaller than the predetermined paper thickness t1 in step P6, the rotational speed Vt of the intermediate roller 14 is set to Vt3 regardless of the original width because the pull-out roller 12 is hardly affected (step P10A). ).

  In this control, the pull-out roller 12 is fixed and the rotation speed of the intermediate roller 14 is set to be variable. With this setting, the number of rollers that need to be controlled for the control is reduced, and the control is easy. Since there is no need to adjust the rotational speed of the upstream pull-out roller 12 from the location where the thickness detection sensor S1 is disposed, the location where the thickness detection sensor S1 is disposed is compared with the case where the speeds of both rollers are controlled. It is also possible to set it further downstream. In order to change the rotation speed of the roller to a desired value, it is necessary to consider the rise time of the motor and so on. Therefore, the thickness detection sensor S1 and the position of the roller to be controlled can be arranged to some extent apart from each other. Is more advantageous.

  By the way, skew of a stiff document occurs when the leading end of the document hits the turn guide unit 40. If the document is long and subject to side fence restrictions at this time, the occurrence of skew is reduced. .

Therefore, the present invention can be controlled as in the flowchart shown in FIG.
In FIG. 8, steps P1 to P6 and P11 to P13 in this figure are the same as steps P1 to P6 and P11 to P13 in FIG. , The length l is detected by the document length sensors 30, 31, 32 (step P1A).

  If the paper thickness t of the original is larger than the predetermined paper thickness t1 in step P6 of FIG. 8, it is determined whether the original length l is longer than l1 (step P7B). The predetermined length l1 at this time is appropriately set according to the length that is restricted by the side fence when the leading edge of the document hits the turn guide portion 40. In this control, since the rotation speed of the pull-out roller 12 is varied and the rotation speed of the intermediate roller 14 is set to be fixed, if it is determined in step P7B that the document length l is shorter than the predetermined length l1, The rotational speed Vp of the pull-out roller 12 is set to Vp1 (step P8B). If it is determined that the document length l is longer than the predetermined length l1, the document is less likely to be skewed by the side fence, so the rotation speed Vp of the pull-out roller 12 is set to Vp2 (step P9C). If the paper thickness t of the original is smaller than the predetermined paper thickness t1 in step 6, the pull-out roller 12 is almost unaffected, so that the rotation speed Vp of the pull-out roller 12 is set to Vp3 regardless of the original length l. Set (step P10B).

  Thereafter, the reading operation similar to the control in FIG. 6 is performed. In this control, the pull-out roller 12 is set to be variable and the intermediate roller 14 is set to be fixed. With this setting, the number of rollers that need to be controlled for the rotational speed is reduced, and the control is facilitated.

  In the above-described embodiment, the thickness of the document is detected by the thickness sensor S1 and controlled based on the thickness sensor S1, but the user can naturally recognize whether the document to be set is thick. The control may be based on the paper thickness information input from the operation panel (not shown), and examples of such control are shown in FIGS. As the paper thickness information method input by the user, it is preferable to input only for thick paper and thin paper, and to be set as plain paper, which is normally considered to be the most when nothing is input.

  FIG. 9 substantially corresponds to the control of FIG. 6 of the above embodiment, and the original set sensor 5 detects the setting of the original (step Q1), and the thick paper information as the paper type information from the main body control unit 111 and When a document feed signal is received (steps Q2 and Q3), it is determined whether or not the paper thickness t of the transported document is thicker than a predetermined paper thickness t1 (step Q4). If the original paper thickness t is thicker than the predetermined paper thickness t1, based on the information, the rotational speed Vt of the intermediate roller 14 is set to Vt1, and the rotational speed Vp of the pull-out roller 12 is set to Vp1 (step Q5). .

  When the paper thickness t of the conveyed document is thinner than t1, it is determined whether or not the document thickness t is larger than a predetermined paper thickness t2 (step Q6). It is judged whether the paper is thin. If the original is plain paper, the rotational speed Vt of the intermediate roller 14 is set to Vt2 and the rotational speed Vp of the pull-out roller 12 is set to Vp2 (step Q7). If the original is thin, the rotational speed Vt of the intermediate roller 14 is set to Vt3. The rotational speed Vp of the roller 12 is set to Vp3. However, the predetermined value of the paper thickness is t1> t2, the predetermined value of the rotation speed of the intermediate roller 14 is Vt1> Vt2> Vt3, and the predetermined value of the rotation speed of the pull-out roller 12 is Vp1 <Vp2 <Vp3 as described above. The relationship between the rotational speed Vt1 of the intermediate roller 14 in the case of thick paper and the rotational speed Vp1 of the pull-out roller 12 is Vt1 ≧ Vp1, and in the case of thin paper, it is Vt3 ≦ Vp3.

When set, the document is fed, separated, and conveyed (step Q9), and the subsequent steps Q10 to Q12 are the same as steps P11 to P13 in FIG.
FIG. 10 substantially corresponds to the control of FIG. 7 of the above embodiment, and steps Q1 to Q4 and Q9 to Q12 of this figure are substantially the same as steps Q1 to Q4 and Q9 to Q12 of FIG. Description is omitted.

  When the paper thickness t of the original is larger than the predetermined paper thickness t1 in step Q4, the width size sensor 13 detects the original width w (step Q5), and whether the original width w is smaller than the predetermined width w1. Judgment is made (step Q6). In this control, the rotation speed of the pull-out roller 12 is fixed and the intermediate roller 14 is set to be variable. Therefore, if the document width w is smaller than the predetermined width w1, the rotation of the intermediate roller 14 is assumed to be affected by the asymmetric arrangement. Speed Vt is set to Vt1 (step Q7A). If the document width w is larger than the predetermined width w1, the influence of the asymmetric arrangement is alleviated, so the rotational speed Vt of the intermediate roller 14 is set to Vt2 (step Q7B). If the paper thickness t of the original is smaller than the predetermined paper thickness t1 in step 4, the pull-out roller 12 is hardly affected, so the rotational speed Vt of the intermediate roller 14 is set to Vt3 (step Q8A).

  The detection of the document width w by the width size sensor 13 in step 5 can be omitted if it can be received together with the cardboard information as the paper type information in step Q2. In this control, the pull-out roller 12 is fixed and the rotation speed of the intermediate roller 14 is set to be variable as in the control of FIG. 7. With this setting, it is necessary to control the rotation speed for such control. This reduces the number of rollers and makes control easier.

  FIG. 11 substantially corresponds to the control of FIG. 8 of the above embodiment, and steps Q1 to Q4 and Q9 to Q12 of this figure are substantially the same as steps Q1 to Q4 and Q9 to Q12 of FIG. Q2 is configured to receive not only cardboard information as paper type information but also length information.

  If the paper thickness t of the original is larger than the predetermined paper thickness t1 in step Q4, it is determined whether the original length l is longer than l1 (step Q5A). If the original length l is shorter than the predetermined length l1. Then, the rotation speed Vp of the pull-out roller 12 is set to Vp1 (step Q6B). If the document length l is longer than the predetermined length l1, the document is less likely to be skewed by the side fence, so the rotation speed Vp of the pull-out roller 12 is set to Vp2 (step Q7C). When the paper thickness t of the original is smaller than the predetermined paper thickness t1 in step 4, the pull-out roller 12 is almost unaffected, so the rotation speed Vp of the pull-out roller 12 is set to Vp3 regardless of the original length l. (Step Q8B).

In this control, the pull-out roller 12 is set to be variable and the intermediate roller 14 is set to be fixed. With this setting, the number of rollers that need to be controlled for the rotational speed is reduced, and the control is facilitated.
Thus, although control which does not use thickness sensor S1 was demonstrated in this embodiment (FIGS. 9-11), this invention can also use together thickness sensor S1 and the input of the paper type information by a user. . For example, when there is no user input information, control is performed using information detected by the thickness sensor S1, and when there is a user input, the paper type information may be preferentially controlled.

FIG. 12 is a control flow showing still another embodiment of the present invention.
In FIG. 12, when the document setting sensor 5 detects the setting of a document (step R1), the main body control unit 111 pulls out a preset pull-out roller 12 based on paper type information, which is paper type information, document width information, and document length information. And the rotational speed of the intermediate roller 14 is received (step R2). That is, the optimum rotation speeds of the pull-out roller 12 and the intermediate roller 14 that are unlikely to cause skew are received from the thick paper information, width information, and length information of the document.

  When a document feed signal is received (step R3), the rotation speeds of the pull-out roller 12 and the intermediate roller 14 are set to rotation speeds Vtu and Vpu suitable for the document to be fed (step R4). Thereafter, steps R5 to R8 are controlled in the same manner as steps Q9 to Q12 in FIG.

  In this example, the rotation speeds of the intermediate roller 14 and the pull-out roller 12 are directly specified by the actual values Vtu and Vpu from the main body, but can be implemented by a more indirect method. For example, the linear velocity tables “(Vt1, Vp1), (Vt2, Vp2), (Vt3, Vp3)” corresponding to the indexes “1, 2, 3,.・ ”May be used.

  In the embodiment described above, the paper thickness is controlled to be proportional to the strength of the waist (rigidity). However, there is a paper whose thickness is firm compared to the thickness, such as an original made of coated paper. In the case of such a special document, when the user inputs information to that effect from the operation panel, a conveying action suitable for the document can be obtained.

11 Butting sensor
12 Pull-out roller 13 Document width sensor 14 Intermediate roller 30, 31, 32 Document length sensor 40 Turn guide section S1 Thickness detection sensor

Japanese Patent No. 3964121

Claims (12)

A turn guide unit is provided for guiding the sheet to be substantially reversed in a conveyance path through which the sheet is conveyed, and a first conveyance roller and a second conveyance roller downstream thereof are provided on the upstream side of the turn guide unit in the sheet conveyance direction. In the sheet conveying apparatus,
A detection unit that is arranged in the conveyance path and detects the sheet type of the sheet, and rotation of at least one of the first conveyance roller and the second conveyance roller according to the sheet type of the sheet detected by the detection unit Control means for varying the speed, and the control means variably controls the rotational speed of the rollers so that the sheet conveying speeds of the first conveying roller and the second conveying roller are substantially the same. Sheet transport device.   The sheet conveying apparatus according to claim 1, wherein the detecting unit includes a thickness detecting unit that detects a sheet thickness, and the control unit detects the thickness of the first conveying roller according to the sheet thickness detected by the thickness detecting unit. A sheet conveying apparatus that controls a rotation speed of at least one of the second conveying rollers.   The sheet conveying apparatus according to claim 1, wherein the detection unit includes a thickness detection unit that detects a sheet thickness, and a width detection unit that detects a width of the sheet, and the sheet thickness detected by the thickness detection unit and The sheet conveying apparatus, wherein the control unit controls a rotation speed of at least one of the first conveying roller and the second conveying roller according to the sheet width detected by the width detecting unit.   2. The sheet conveying apparatus according to claim 1, wherein the detecting means includes a thickness detecting means for detecting a sheet thickness, and a length detecting means for detecting a length in the sheet conveying direction. The control means controls the rotational speed of at least one of the first conveying roller and the second conveying roller according to the detected sheet thickness and the sheet length detected by the length detecting means. Conveying device. A turn guide unit is provided for guiding the sheet to be substantially reversed in a conveyance path through which the sheet is conveyed, and a first conveyance roller and a second conveyance roller downstream thereof are provided on the upstream side of the turn guide unit in the sheet conveyance direction. In the sheet conveying apparatus,
A paper type designating unit for designating the paper type of the sheet, and a rotation speed of at least one of the first transporting roller and the second transporting roller is variable according to the paper type of the sheet designated by the paper type designating unit. And a control unit that variably controls the rotational speed of the rollers so that the sheet transport speeds of the first transport roller and the second transport roller are substantially the same. apparatus.   6. The sheet conveying apparatus according to claim 5, wherein the paper type designation means designates information relating to the rigidity of the sheet, and the control means designates the first conveying roller according to the designated rigidity of the sheet. And a sheet conveying apparatus that controls a rotation speed of at least one of the second conveying rollers.   7. The sheet conveying apparatus according to claim 5, wherein the paper type designating unit designates sheet thickness information, and the control unit determines the rigidity strength from the sheet thickness information. A sheet conveying apparatus that controls a rotation speed of at least one of a conveying roller and the second conveying roller.   8. The sheet conveying apparatus according to claim 1, wherein the control unit variably controls the rotation speeds of both the first conveying roller and the second conveying roller. .   8. A sheet conveying apparatus according to claim 1, wherein the control means makes the rotation speed of the first conveyance roller constant and variably controls the rotation speed of the second conveyance roller. Conveying device.   8. The sheet conveying apparatus according to claim 1, wherein the control unit makes the rotation speed of the second conveyance roller constant and variably controls the rotation speed of the first conveyance roller. Conveying device.   An original reading apparatus that conveys an original using the sheet conveying apparatus according to claim 1.   An image forming apparatus that records and forms an image read by the document reading device according to claim 11.

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